Answer
$t = 4.71~s$
Work Step by Step
We can find the maximum possible acceleration such that the force of static friction can provide the required force to accelerate the toolbox.
$F_f = ma$
$mg~\mu_s = ma$
$a = g~\mu_s = (9.80~m/s^2)(0.650)$
$a = 6.37~m/s^2$
We can find the time to accelerate to $v = 30.0~m/s$.
$t = \frac{v-v_0}{a} = \frac{30.0~m/s-0}{6.37~m/s^2}$
$t = 4.71~s$